Bug 22613: Add GET endpoint /patrons/{patron_id}/checkouts

Bug 22613: Add GET endpoint /patrons/{patron_id}/checkouts

This patch adds a new endpoint, for fetching checkouts from a specific
patron.

Test plan:

1. Apply this patch
2. Run:
   $ ktd --shell
  k$ prove t/db_dependent/api/v1/patrons_checkouts.t
=> SUCCESS: Tests pass!
3. Run:
   $ curl -v -s -u koha:koha --request GET \
        http://kohadev.local/api/v1/patrons/{id}/checkouts
test with query parameters (they are the same as for /patrons/{id}/holds
=> SUCCESS: The API works!

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>